The blood of persons having diseases involving tissue degeneration often contains elevated levels of membrane fragments. See generally K Shinkai et al 32 Can. Res. 2307-2313 (1972). The disclosure of this article and of all other articles and patents referred to herein are incorporated by reference as if fully set forth herein. One such fragment, "FHAP", has been separated by electrophoresis (see e.g. U.S. Pat. No. 4,166,766) and was first detected by its alkaline phosphatase activity Its unique (fast) electrophoretic mobility and its sensitivity to inhibition by homoarginine are the basis of its acronym. In this regard, FHAP is faster than liver alkaline phosphatase in certain types of cellulose acetate electrophoresis.
The acronym "FHAP" was originally developed to name a complex that is the fast homoarginine-sensitive alkaline phosphatase cancer marker described in U.S. Pat. No. 4,166,766. The complex was originally thought to be an isoenzyme. It has now been learned by the applicants that while the FHAP complex does contain the alkaline phosphatase enzyme, it also contains other enzymes. Nevertheless, the acronym has continued to be used to refer to the complex and is used in that manner herein.
Research has shown that FHAP is a marker for a wide variety of cancers. See e.g. R. Bowser-Finn et al., 7 Tumour Biology 343-352 (1986). While FHAP was initially assumed to be an isoenzyme, the substance is in fact a large complex containing, inter alia, alkaline phosphatase, leucine aminopeptidase, gamma-glutamyl transferase and 5' nucleotidase. Since these enzymes are enzymes present in membranes, it is now believed that FHAP is comprised of fragments of cell membranes that are generated during various stages of certain diseases.
While FHAP levels in serum may be measured by cellulose polyacetate electrophoresis, the relatively poor sensitivity of this method limits its usefulness to a small number of cases in which the FHAP concentration approaches the free liver/bone/kidney alkaline phosphatase concentration. FHAP levels in serum may also be measured by an ion-exchange separation and the enzyme assay detailed in U.S. Pat. No. 4,166,766. However, this requires a substantial amount of serum per determination and undue cost and time. Also, the sensitivity of the assay may in some cases permit detection of FHAP-like material which is present in the serum of healthy controls.
Attempts have been made to develop antibodies to FHAP as a first step towards developing immunoassays. However, prior to the present invention these efforts have proved unsuccessful. A further problem is that while prior art assays gave information as to quantitative levels, they told little about the type of cancer or the stage of cancer. Thus, a need exists for a FHAP test which provides a greater amount of information about the disease and which is easier to use.